Intensive Aquaculture and Environmental Welfare: Ecosystem Considerations

Intensive aquaculture affects not only farmed animals but wild ecosystems and their inhabitants. Welfare thinking must encompass these broader ecological impacts.

Key Facts

Net-pen salmon farming generates nutrient and organic waste that can cause local oxygen depletion and benthic ecosystem damage beneath pens.
Escaped farmed salmon can interbreed with wild populations, reducing the genetic fitness of wild stocks.
Wild fish harvested for fishmeal to feed carnivorous aquaculture species represent a welfare cost that is separate from farmed animal welfare.
An estimated 0.7-3 kg of wild fish protein is consumed to produce 1 kg of farmed salmon, depending on feed composition.
Sea lice from salmon farms can transmit to wild salmon and sea trout populations, causing significant mortality.
Closed-containment systems — land-based recirculating aquaculture systems (RAS) — address most environmental externalities at higher cost.
Ecosystem approach to aquaculture considers the wider ecological impacts alongside individual fish welfare.
Marine protected areas and fallowing requirements provide regulatory tools to reduce environmental welfare externalities.

Welfare Considerations

Welfare thinking in aquaculture must extend beyond the individual farmed animals to encompass the welfare of wild animals affected by aquaculture operations. Wild salmon and sea trout parasitised by farm-sourced sea lice experience significant welfare harm; benthic organisms smothered by organic waste suffer welfare consequences; and wild fish harvested for fishmeal and fish oil incur welfare costs in their capture and processing. These wider welfare impacts are frequently excluded from aquaculture welfare assessments that focus only on farmed species. Comprehensive aquaculture welfare requires ecosystem approaches that consider the full range of animal welfare implications of production systems, driving choices toward closed-containment systems that internalise environmental impacts.

What You Can Do

Choose aquaculture products certified by schemes that address environmental as well as individual animal welfare.
Support the transition to land-based recirculating aquaculture systems that reduce ecosystem impacts.
Advocate for effective sea lice management regulations that protect wild salmonid populations.
Support marine protected areas and fallowing requirements for sea-pen aquaculture operations.
Reduce consumption of aquaculture products from systems with documented environmental welfare externalities.
Support research into plant-based and alternative protein sources for aquaculture feed to reduce fishmeal demand.